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Keywords = Appalachian climate

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25 pages, 19085 KiB  
Article
Spatiotemporal Vegetation Dynamics, Forest Loss, and Recovery: Multidecadal Analysis of the U.S. Triple Crown National Scenic Trail Network
by Amber R. Ignatius, Ashley N. Annis, Casey A. Helton, Alec W. Reeb and Dylan F. Ricke
Remote Sens. 2025, 17(7), 1142; https://doi.org/10.3390/rs17071142 - 24 Mar 2025
Cited by 1 | Viewed by 892
Abstract
The U.S. National Scenic Trail system, encompassing over 12,000 km of hiking trails along the Appalachian Trail (AT), Continental Divide Trail (CDT), and Pacific Crest Trail (PCT), provides critical vegetation corridors that protect diverse forest, savannah, and grassland ecosystems. These ecosystems represent essential [...] Read more.
The U.S. National Scenic Trail system, encompassing over 12,000 km of hiking trails along the Appalachian Trail (AT), Continental Divide Trail (CDT), and Pacific Crest Trail (PCT), provides critical vegetation corridors that protect diverse forest, savannah, and grassland ecosystems. These ecosystems represent essential habitats facing increasing environmental pressures. This study offers a landscape-scale analysis of the vegetation dynamics across a 2 km wide conservation corridor (20,556 km2), utilizing multidecadal Landsat and MODIS satellite data via Google Earth Engine API to assess the vegetation health, forest disturbance recovery, and phenological shifts. The results reveal that forest loss, primarily driven by wildfire, impacted 1248 km2 of land (9.5% in the AT, 39% in the CDT, and 51% in the PCT) from 2001 to 2023. Moderate and severe wildfires in the PCT (713 km2 burn area) and CDT (350 km2 burn area) corridors exacerbated the vegetation stress and facilitated the transition from forest to grassland. LandTrendr analysis at 15 sample sites revealed slow, multi-year vegetation recovery in the CDT and PCT corridors based on the temporal segmentation and vegetation spectral indices (NBR, NDVI, NDWI, Tasseled Cap). The post-disturbance NBR values remained significantly reduced, averaging 0.31 at five years post-event compared to 0.6 prior to the disturbance. Variations in the vegetation phenology were documented, with no significant trends in the seasonal advancement or delay. This study establishes a robust baseline for vegetation change across the trail system, highlighting the need for further research to explore localized trends. Given the accelerating impacts of climate change and wildfire frequency, the findings underscore the necessity of adaptive conservation strategies to guide vegetation management and ensure the long-term stability and sustainability of vegetation cover in these vital conservation areas. Full article
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15 pages, 2488 KiB  
Article
Wetland Creation and Reforestation of Legacy Surface Mines in the Central Appalachian Region (USA): A Potential Climate-Adaptation Approach for Pond-Breeding Amphibians?
by Lauren Sherman, Christopher D. Barton, Jacquelyn C. Guzy, Rebecca N. Davenport, John J. Cox, Jeffery L. Larkin, Todd Fearer, Jillian C. Newman and Steven J. Price
Water 2024, 16(9), 1202; https://doi.org/10.3390/w16091202 - 23 Apr 2024
Cited by 1 | Viewed by 2237
Abstract
Habitat restoration and creation within human-altered landscapes can buffer the impacts of climate change on wildlife. The Forestry Reclamation Approach (FRA) is a coal surface mine reclamation practice that enhances reforestation through soil decompaction and the planting of native trees. Recently, wetland creation [...] Read more.
Habitat restoration and creation within human-altered landscapes can buffer the impacts of climate change on wildlife. The Forestry Reclamation Approach (FRA) is a coal surface mine reclamation practice that enhances reforestation through soil decompaction and the planting of native trees. Recently, wetland creation has been coupled with FRA to increase habitat available for wildlife, including amphibians. Our objective was to evaluate the response of pond-breeding amphibians to the FRA by comparing species occupancy, richness, and abundance across two FRA age-classes (2–5-year and 8–11-year reclaimed forests), traditionally reclaimed sites that were left to naturally regenerate after mining, and in mature, unmined forests in the Monongahela National Forest (West Virginia, USA). We found that species richness and occupancy estimates did not differ across treatment types. Spotted Salamanders (Ambystoma maculatum) and Eastern Newts (Notophthalmus viridescens) had the greatest estimated abundances in wetlands in the older FRA treatment. Additionally, larger wetlands had greater abundances of Eastern Newts, Wood Frogs (Lithobates sylvaticus), and Green Frogs (L. clamitans) compared to smaller wetlands. Our results suggest that wetland creation and reforestation increases the number of breeding sites and promotes microhabitat and microclimate conditions that likely maximize the resilience of pond-breeding amphibians to anticipated climate changes in the study area. Full article
(This article belongs to the Special Issue Restoration of Wetlands for Climate Change Mitigation)
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15 pages, 3909 KiB  
Article
Trechus (Coleoptera: Carabidae) of Appalachia: A Phylogenetic Insight into the History of High Elevation Leaf Litter Communities
by Patricia L. S. Wooden and Michael S. Caterino
Diversity 2024, 16(4), 212; https://doi.org/10.3390/d16040212 - 30 Mar 2024
Cited by 2 | Viewed by 2155
Abstract
Elevation gradients provide a wealth of habitats for a wide variety of organisms. The southern Appalachian Mountains in eastern United States are known for their high biodiversity and rates of endemism in arthropods, including in high-elevation leaf-litter taxa that are often found nowhere [...] Read more.
Elevation gradients provide a wealth of habitats for a wide variety of organisms. The southern Appalachian Mountains in eastern United States are known for their high biodiversity and rates of endemism in arthropods, including in high-elevation leaf-litter taxa that are often found nowhere else on earth. Trechus Clairville (Coleoptera: Carabidae) is a genus of litter inhabitants with a near-global distribution and over 50 Appalachian species. These span two subgenera, Trechus s. str. and Microtrechus Jeannel, largely restricted to north and south of the Asheville basin, respectively. Understanding the diversification of these 3–5 mm flightless beetles through geological time can provide insights into how the litter-arthropod community has responded to historical environments, and how they may react to current and future climate change. We identified beetles morphologically and sequenced six genes to reconstruct a phylogeny of the Appalachian Trechus. We confirmed the Asheville Basin as a biogeographical barrier with a split between the north and south occurring towards the end of the Pliocene. Finer scale biogeography, including mountain-range occupancy, was not a reliable indication of relatedness, with group ranges overlapping and many instances of species-, species group-, and subgeneric sympatry. This may be because of the recent divergence between modern species and species groups. Extensive taxonomic revision of the group is required for Trechus to be useful as a bioindicator, but their high population density and speciose nature make them worth additional time and resources. Full article
(This article belongs to the Section Biodiversity Conservation)
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19 pages, 5458 KiB  
Article
Richness and Elevation Patterns of a Stonefly (Insecta, Plecoptera) Community of a Southern Appalachian Mountains Watershed, USA
by Madeline L. Metzger and Scott A. Grubbs
Ecologies 2023, 4(3), 442-460; https://doi.org/10.3390/ecologies4030028 - 22 Jun 2023
Cited by 2 | Viewed by 2186
Abstract
Protected areas are relatively free of human disturbance, are especially common in montane regions, and provide opportunities to study native fauna and flora. Stoneflies are model organisms to assess present and future environmental changes. While stoneflies inhabit cold lakes and a wide size [...] Read more.
Protected areas are relatively free of human disturbance, are especially common in montane regions, and provide opportunities to study native fauna and flora. Stoneflies are model organisms to assess present and future environmental changes. While stoneflies inhabit cold lakes and a wide size range of lotic systems, diversity is greatest in streams draining mountain landscapes. This study addressed seasonal and elevation patterns of a stonefly fauna inhabiting a protected landscape draining the eastern flank of Mount Mitchell, the highest point of the Appalachian Mountains, USA. In total, 58 species were collected with estimated richness values ranging from 63 to 65. Species determinations were assisted with an integrative molecular approach using the mitochondrial barcode gene. Sampling during spring yielded the most species seasonally. Although certain species were only found at lower or higher sites, several were collected from across a broad range of elevations. Roughly 1/3 (21 = 36%) of the fauna present is known only from the southern Appalachian Highlands region, including one species described as new during this study. The assemblage reported here, however, did not closely align with other Appalachian fauna. Overall, well-structured faunal research continues to be important in light of continuing habitat modifications and climate change. Full article
(This article belongs to the Special Issue Feature Papers of Ecologies 2023)
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14 pages, 2073 KiB  
Article
Seasonal Lifting Condensation Level Trends: Implications of Warming and Reforestation in Appalachia’s Deciduous Forest
by Evan Kutta and Jason A. Hubbart
Atmosphere 2023, 14(1), 98; https://doi.org/10.3390/atmos14010098 - 2 Jan 2023
Cited by 1 | Viewed by 2790
Abstract
Lifting condensation level (LCL) has long been used to estimate cloud base heights. However, spatial and temporal patterns of cloud bases embedded within atmospheric currents flowing over mountainous terrain still need to be more adequately described. To advance understanding, hourly observations of barometric [...] Read more.
Lifting condensation level (LCL) has long been used to estimate cloud base heights. However, spatial and temporal patterns of cloud bases embedded within atmospheric currents flowing over mountainous terrain still need to be more adequately described. To advance understanding, hourly observations of barometric pressure and ambient and dew point temperatures from 1948 to 2017 were acquired for seven airports located at 40.21° N (average) and crossing the Allegheny Mountains of the northeastern United States. Daily LCL trends were quantified, and large positive (2.3 m yr−1) and negative (−1.3 m yr−1) LCL trends were found to be greatest near seasonal transition dates (17 April and 9 November 2022). Cool season LCLs (795 m) increased significantly (p < 0.007) at five sites resulting in an average LCL increase of 81 m and implying a deeper and drier sub-cloud layer. Average warm season LCLs (773 m) decreased by 23 m, suggesting a deeper convective cloud layer and less sub-cloud evaporation that may facilitate higher hydrometeor growth and precipitation rates. Collective results indicate divergent seasonally averaged LCLs characterized by more rapid seasonal transitions, warmer and less cloudy cool seasons, and cloudier and more humid warm seasons that may be partly attributable to aggressive reforestation and contribute to more significant rainfall events and higher flood risks. Full article
(This article belongs to the Section Biosphere/Hydrosphere/Land–Atmosphere Interactions)
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33 pages, 1346 KiB  
Review
Analysis of Regulatory Framework for Produced Water Management and Reuse in Major Oil- and Gas-Producing Regions in the United States
by Wenbin Jiang, Lu Lin, Xuesong Xu, Huiyao Wang and Pei Xu
Water 2022, 14(14), 2162; https://doi.org/10.3390/w14142162 - 8 Jul 2022
Cited by 20 | Viewed by 10703
Abstract
The rapid development of unconventional oil and gas (O&G) extraction around the world produces a significant amount of wastewater that requires appropriate management and disposal. Produced water (PW) is primarily disposed of through saltwater disposal wells, and other reuse/disposal methods include using PW [...] Read more.
The rapid development of unconventional oil and gas (O&G) extraction around the world produces a significant amount of wastewater that requires appropriate management and disposal. Produced water (PW) is primarily disposed of through saltwater disposal wells, and other reuse/disposal methods include using PW for hydraulic fracturing, enhanced oil recovery, well drilling, evaporation ponds or seepage pits within the O&G field, and transferring PW offsite for management or reuse. Currently, 1–2% of PW in the U.S. is used outside the O&G field after treatment. With the considerable interest in PW reuse to reduce environmental implications and alleviate regional water scarcity, it is imperative to analyze the current regulatory framework for PW management and reuse. In the U.S., PW is subject to a complex set of federal, state, and sometimes local regulations to address the wide range of PW management, construction, and operation practices. Under the supervision of the U.S. Environment Protection Agency (U.S. EPA), different states have their own regulatory agencies and requirements based on state-specific practices and laws. This study analyzed the regulatory framework in major O&G-producing regions surrounding the management of PW, including relevant laws and jurisdictional illustrations of water rules and responsibilities, water quality standards, and PW disposal and current/potential beneficial reuse up to early 2022. The selected eastern states (based on the 98th meridian designated by the U.S. EPA as a tool to separate discharge permitting) include the Appalachian Basin (Marcellus and Utica shale areas of Pennsylvania, Ohio, and West Virginia), Oklahoma, and Texas; and the western states include California, Colorado, New Mexico, and Wyoming. These regions represent different regulations; climates; water quantities; quality diversities; and geologic, geographic, and hydrologic conditions. This review is particularly focused on the water quality standards, reuse practices and scenarios, risks assessment, knowledge gaps, and research needs for the potential reuse of treated PW outside of O&G fields. Given the complexity surrounding PW regulations and rules, this study is intended as preliminary guidance for PW management, and for identifying the knowledge gaps and research needs to reduce the potential impacts of treated PW reuse on the environment and public health. The regulations and experiences learned from these case studies would significantly benefit other states and countries with O&G sources for the protection of their environment and public health. Full article
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11 pages, 2044 KiB  
Technical Note
Assessment of Canopy Health with Drone-Based Orthoimagery in a Southern Appalachian Red Spruce Forest
by Ryley C. Harris, Lisa M. Kennedy, Thomas J. Pingel and Valerie A. Thomas
Remote Sens. 2022, 14(6), 1341; https://doi.org/10.3390/rs14061341 - 10 Mar 2022
Cited by 13 | Viewed by 4116
Abstract
Consumer-grade drone-produced digital orthoimagery is a valuable tool for conservation management and enables the low-cost monitoring of remote ecosystems. This study demonstrates the applicability of RGB orthoimagery for the assessment of forest health at the scale of individual trees in a 46-hectare plot [...] Read more.
Consumer-grade drone-produced digital orthoimagery is a valuable tool for conservation management and enables the low-cost monitoring of remote ecosystems. This study demonstrates the applicability of RGB orthoimagery for the assessment of forest health at the scale of individual trees in a 46-hectare plot of rare southern Appalachian red spruce forest on Whitetop Mountain, Virginia. We used photogrammetric Structure from Motion software Pix4Dmapper with drone-collected imagery to generate a mosaic for point cloud reconstruction and orthoimagery of the plot. Using 3-band RBG digital orthoimagery, we visually classified 9402 red spruce individuals, finding 8700 healthy (92.5%), 251 declining/dying (2.6%), and 451 dead (4.8%). We mapped individual spruce trees in each class and produced kernel density maps of health classes (live, dead, and dying). Our approach provided a nearly gap-free assessment of the red spruce canopy in our study site, versus a much more time-intensive field survey. Our maps provided useful information on stand mortality patterns and canopy gaps that could be used by managers to identify optimal locations for selective thinning to facilitate understory sapling regeneration. This approach, dependent mainly on an off-the-shelf drone system and visual interpretation of orthoimagery, could be applied by land managers to measure forest health in other spruce, or possibly spruce-fir, communities in the Appalachians. Our study highlights the usefulness of drone-produced orthoimagery for conservation monitoring, presenting a valid and accessible protocol for the monitoring and assessment of forest health in remote spruce, and possibly other conifer, populations. Adoption of drone-based monitoring may be especially useful in light of climate change and the possible displacement of southern Appalachian red spruce (and spruce-fir) ecosystems by the upslope migration of deciduous trees. Full article
(This article belongs to the Special Issue Drones for Ecology and Conservation)
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23 pages, 3251 KiB  
Article
Evidence of Mid-Holocene (Northgrippian Age) Dry Climate Recorded in Organic Soil Profiles in the Central Appalachian Mountains of the Eastern United States
by Mitzy L. Schaney, James S. Kite, Christopher R. Schaney and James A. Thompson
Geosciences 2021, 11(11), 477; https://doi.org/10.3390/geosciences11110477 - 20 Nov 2021
Cited by 4 | Viewed by 3125
Abstract
Peatlands in Canaan Valley National Wildlife Refuge hold a pedomemory of Pleistocene and Holocene climatic fluctuations in the central Appalachian Mountains of the eastern United States. A field investigation profiling 88 organic soil profiles, coupled with 52 radiocarbon dates and peat accumulation rates, [...] Read more.
Peatlands in Canaan Valley National Wildlife Refuge hold a pedomemory of Pleistocene and Holocene climatic fluctuations in the central Appalachian Mountains of the eastern United States. A field investigation profiling 88 organic soil profiles, coupled with 52 radiocarbon dates and peat accumulation rates, revealed a distinct sequence of organic soil horizons throughout five study areas. The dominantly anaerobic lower portions of the organic soil profiles consist of varied thicknesses of hemic and sapric soil materials, typically layered as an upper hemic horizon, underlain by a sapric horizon, underlain by another hemic horizon. Peat deposition began after the Last Glacial Maximum with relatively high Heinrich Stadial 1 accumulation rates to form the lowest hemic horizon. Peat accumulated at significantly slower rates as the climate continued to warm in the early Holocene Greenlandian Age. However, between 10,000 and 4200 cal yr BP peat accumulation decreased further and the decomposition of previously deposited peat prevailed, forming the sapric horizon. This interval of greater decomposition indicates a drier climatic with dates spanning the late Greenlandian Age through the Northgrippian Age. The upper hemic horizon within the anaerobic portion of the soil profile formed from high peat accumulation rates during the wetter late Holocene Meghalayan Age. Full article
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13 pages, 1506 KiB  
Review
Sustainable Management of Central Appalachian Red Spruce
by Eric Yetter, Sophan Chhin and John P. Brown
Sustainability 2021, 13(19), 10871; https://doi.org/10.3390/su131910871 - 30 Sep 2021
Cited by 3 | Viewed by 2676
Abstract
Red spruce (Picea rubens) was historically an important and dominant timber species in the central Appalachian mountain range. The tree species is now found in a small fraction of its original home range. Threatened and endangered organisms such as the Cheat [...] Read more.
Red spruce (Picea rubens) was historically an important and dominant timber species in the central Appalachian mountain range. The tree species is now found in a small fraction of its original home range. Threatened and endangered organisms such as the Cheat Mountain Salamander (Plethodon nettingi) rely on red spruce associated forests for survival. This review provides a background on the history of forest management of red spruce in the central Appalachian region. A meta-analysis was conducted on recent literature (published 2000 or later) of red spruce in the central Appalachian region to highlight key management and conservation concerns. In particular, forest health concerns related to air pollution and climatic stress also are addressed. Approaches to examine the impact of environmental factors on red spruce site productivity are covered. This review also provides sustainable management options for restoration of red spruce in the central Appalachian mountain range. Full article
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13 pages, 3513 KiB  
Article
Anamorphic Site Index Curves for Central Appalachian Red Spruce in West Virginia, USA
by Eric Yetter, John Brown and Sophan Chhin
Forests 2021, 12(1), 94; https://doi.org/10.3390/f12010094 - 16 Jan 2021
Cited by 2 | Viewed by 3096
Abstract
Traditional site index curves are frequently produced for shade-intolerant species but are scarce for shade-tolerant species. Red spruce (Picea rubens Sarg.) can be found in three distinct geographic regions (northern, central, and southern) within the Appalachian Mountains. The one commonly used set [...] Read more.
Traditional site index curves are frequently produced for shade-intolerant species but are scarce for shade-tolerant species. Red spruce (Picea rubens Sarg.) can be found in three distinct geographic regions (northern, central, and southern) within the Appalachian Mountains. The one commonly used set of red spruce site index curves is over ninety years old. A definite need exists for a modern, regionally applicable set of site index curves. This research sampled 83 plots randomly located in the central Appalachians of West Virginia. Three sets of anamorphic site index curves were created after careful examination of height models built using Chapman-Richards and Meyer functions. One set of curves was constructed with traditional age height pairs. The second utilized a suppression-corrected age and height pair. The third set examined diameter at breast height (DBH) and height pairs. Fit statistics indicated better performance for the suppression-corrected age–height pair site index and the DBH–height pair site index versus the traditional age–height pair models. Site index conversion equations were also investigated for the red spruce age-corrected site index. Linear regression was used to determine significant geographic and climate variables and the utility of including site index values for red maple (Acer rubrum L.) and yellow birch (Betula alleghaniensis Britton) in the model to predict red spruce site index. Significant models were found for varying combinations of species site index, climate, and geographic variables with R2adj in the range of 0.139–0.455. These new site index curves and conversion equations should provide utility for site productivity estimation and growth and yield modeling while aiding in restoration efforts for this important central Appalachian species. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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20 pages, 5031 KiB  
Case Report
Quantifying Escherichia coli and Suspended Particulate Matter Concentrations in a Mixed-Land Use Appalachian Watershed
by Fritz Petersen and Jason A. Hubbart
Water 2020, 12(2), 532; https://doi.org/10.3390/w12020532 - 14 Feb 2020
Cited by 16 | Viewed by 4773
Abstract
The relationships between Escherichia (E) coli concentration, suspended particulate matter (SPM) particle size class, and land use practices are important in reducing the bacterium’s persistence and health risks. However, surprisingly few studies have been performed that quantify these relationships. Conceivably, such information would [...] Read more.
The relationships between Escherichia (E) coli concentration, suspended particulate matter (SPM) particle size class, and land use practices are important in reducing the bacterium’s persistence and health risks. However, surprisingly few studies have been performed that quantify these relationships. Conceivably, such information would advance mitigation strategies for practices that address specific SPM size classes and, by proxy, E. coli concentration. To advance this needed area of research, stream water was sampled from varying dominant land use practices in West Run Watershed, a representative mixed-land use Appalachian watershed of West Virginia in the eastern USA. Water samples were filtered into three SPM intervals (<5 µm; 5 µm to 60 μm; and >60 μm) and the E. coli concentration (colony forming units, CFU) and SPM of each interval was quantified. Statistically significant relationships were identified between E. coli concentrations and size intervals (α < 0.0001), and SPM (α = 0.05). The results show a predominance (90% of total) of E. coli CFUs in the <5 μm SPM interval. The results show that land use practices impact the relationships between SPM and E. coli concentrations. Future work should include additional combined factors that influence bacterial CFUs and SPM, including hydrology, climate, geochemistry and nutrients. Full article
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23 pages, 5933 KiB  
Article
Twenty-First Century Streamflow and Climate Change in Forest Catchments of the Central Appalachian Mountains Region, US
by Brandi Gaertner, Rodrigo Fernandez and Nicolas Zegre
Water 2020, 12(2), 453; https://doi.org/10.3390/w12020453 - 8 Feb 2020
Cited by 8 | Viewed by 4565
Abstract
Forested catchments are critical sources of freshwater used by society, but anthropogenic climate change can alter the amount of precipitation partitioned into streamflow and evapotranspiration, threatening their role as reliable fresh water sources. One such region in the eastern US is the heavily [...] Read more.
Forested catchments are critical sources of freshwater used by society, but anthropogenic climate change can alter the amount of precipitation partitioned into streamflow and evapotranspiration, threatening their role as reliable fresh water sources. One such region in the eastern US is the heavily forested central Appalachian Mountains region that provides fresh water to local and downstream metropolitan areas. Despite the hydrological importance of this region, the sensitivity of forested catchments to climate change and the implications for long-term water balance partitioning are largely unknown. We used long-term historic (1950–2004) and future (2005–2099) ensemble climate and water balance data and a simple energy–water balance model to quantify streamflow sensitivity and project future streamflow changes for 29 forested catchments under two future Relative Concentration Pathways. We found that streamflow is expected to increase under the low-emission pathway and decrease under the high-emission pathway. Furthermore, despite the greater sensitivity of streamflow to precipitation, larger increases in atmospheric demand offset increases in precipitation-induced streamflow, resulting in moderate changes in long-term water availability in the future. Catchment-scale results are summarized across basins and the region to provide water managers and decision makers with information about climate change at scales relevant to decision making. Full article
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13 pages, 1111 KiB  
Article
Well-Aerated Southern Appalachian Forest Soils Demonstrate Significant Potential for Gaseous Nitrogen Loss
by Peter Baas, Jennifer D. Knoepp and Jacqueline E. Mohan
Forests 2019, 10(12), 1155; https://doi.org/10.3390/f10121155 - 17 Dec 2019
Cited by 5 | Viewed by 2971
Abstract
Understanding the dominant soil nitrogen (N) cycling processes in southern Appalachian forests is crucial for predicting ecosystem responses to changing N deposition and climate. The role of anaerobic nitrogen cycling processes in well-aerated soils has long been questioned, and recent N cycling research [...] Read more.
Understanding the dominant soil nitrogen (N) cycling processes in southern Appalachian forests is crucial for predicting ecosystem responses to changing N deposition and climate. The role of anaerobic nitrogen cycling processes in well-aerated soils has long been questioned, and recent N cycling research suggests it needs to be re-evaluated. We assessed gross and potential rates of soil N cycling processes, including mineralization, nitrification, denitrification, nitrifier denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) in sites representing a vegetation and elevation gradient in the U.S. Department of Agriculture (USDA) Forest Service Experimental Forest, Coweeta Hydrologic Laboratory in southwestern North Carolina, USA. N cycling processes varied among sites, with gross mineralization and nitrification being greatest in high-elevation northern hardwood forests. Gaseous N losses via nitrifier denitrification were common in all ecosystems but were greatest in northern hardwood. Ecosystem N retention via DNRA (nitrification-produced NO3 reduced to NH4) ranged from 2% to 20% of the total nitrification and was highest in the mixed-oak forest. Our results suggest the potential for gaseous N losses through anaerobic processes (nitrifier denitrification) are prevalent in well-aerated forest soils and may play a key role in ecosystem N cycling. Full article
(This article belongs to the Section Forest Ecology and Management)
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14 pages, 4696 KiB  
Article
April Vegetation Dynamics and Forest–Climate Interactions in Central Appalachia
by Nathan Shull and Eungul Lee
Atmosphere 2019, 10(12), 765; https://doi.org/10.3390/atmos10120765 - 2 Dec 2019
Cited by 3 | Viewed by 3740
Abstract
The study of land–atmosphere (L–A) interactions is an emerging field in which the effects of the land on the atmosphere are strongly considered. Though this coupled approach is becoming more popular in atmospheric research, L–A interactions are not fully understood, especially in temperate [...] Read more.
The study of land–atmosphere (L–A) interactions is an emerging field in which the effects of the land on the atmosphere are strongly considered. Though this coupled approach is becoming more popular in atmospheric research, L–A interactions are not fully understood, especially in temperate regions. This study provides the first in-depth investigation of L–A interactions and their impacts on near-surface climate conditions in the Appalachian region of the Eastern United States. By way of statistical analysis, we explore vegetation dynamics, L–A interactions, and the consequences for near-surface climate, along with the competing effects of the albedo (energy) and moisture (evapotranspiration and soil moisture) feedback. Based on the results from linear regression, composite, and correlation analyses, we conclude that: (1) a statistically significant increasing trend in April vegetation exists from 1982 to 2015 in central Appalachia; (2) there was empirical evidence that this increasing vegetation trend was significant and altered near-surface climatic conditions, as indicated by significantly enhanced latent heat flux, 2 m-specific humidity, and soil moisture; and (3) the dominant biogeophysical process responsible for the changes in near-surface climate conditions could be the positive moisture feedback process. Full article
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13 pages, 5616 KiB  
Article
Freeze-Thaw Induced Gully Erosion: A Long-Term High-Resolution Analysis
by Ingrid Luffman and Arpita Nandi
Agronomy 2019, 9(9), 549; https://doi.org/10.3390/agronomy9090549 - 13 Sep 2019
Cited by 8 | Viewed by 3018
Abstract
Gullies are significant contributors of sediment to streams in the southeastern USA. This study investigated gully erosion in the clay-rich soils of east Tennessee under a humid subtropical climate. The aims of this study were to (1) estimate long-term erosion rates for different [...] Read more.
Gullies are significant contributors of sediment to streams in the southeastern USA. This study investigated gully erosion in the clay-rich soils of east Tennessee under a humid subtropical climate. The aims of this study were to (1) estimate long-term erosion rates for different gully geomorphic settings, (2) compare patterns of erosion for the different settings, and (3) model the response of gully erosion to freeze-thaw events. Erosion was measured weekly from June 2012 to August 2018 using 105 erosion pins distributed in gully channels, interfluves, and sidewalls. Erosion rates were estimated from average slopes of lines of best fit of pin lengths versus time. Maximum and minimum temperature was calculated daily using an on-site weather station and freeze-thaw events were identified. Gully erosion was modeled using antecedent freeze-thaw activity for the three geomorphic settings. Long-term erosion rates in channels, interfluves, and sidewalls were 2.5 mm/year, 20 mm/year, and 21 mm/year, respectively; however, week-by-week erosion was statistically different between the three settings, indicating different erosive drivers. Models of erosion with lagged freeze-thaw variables explained up to 34.8% of the variability in erosion variables; sidewall erosion was most highly related to freeze-thaw activity. Freeze-thaw in prior weeks was an important variable in all erosion models. Full article
(This article belongs to the Special Issue Surface Runoff and Soil Erosion under Various Climate Conditions)
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